Manufacture of petroleum coke

ABSTRACT

Clusters of petroleum coke pellets are made by the steps of dispersing particulate carbon seed particles in a high boiling petroleum oil, heating the seeded oil in a coking heater under conditions of controlled cracking, and introducing the effluent from the heater into a coke drum where the seed particles serve as nucleating agents in the formation of clusters of petroleum coke pellets.

llite States Patent Schlinger et al.

[451 *Dec. 3, 1974 MANUFACTURE OF PETROLEUM COKE Inventors: Warren G.Schlinger, Pasadena,

Calif.; Harold C. Kaufman; Carroll L. Crawley, both of Houston, Tex.

Texaco Inc., New York, NY. by said Schlinger and Kaufman Assignee:

Notice: The portion of the term of this patent subsequent to June 27,1989, has been disclaimed.

Filed: Feb. 23, 1972 Appl. No.: 228,587

Related US. Application Data Division of Ser. No. 831,548, June 9, 1969,Pat. No. 3,673,080.

US. Cl. 44/24, 44/10 C Int. Cl C10] 5/00 Field of Search 423/445, 449,450;

[56] References Cited UNITED STATES PATENTS 2,340,974 2/1944 Myers208/52 2,358,573 9/1944 Hemminger 208/96 X 3,498,906 3/1970 Bogart eta1... 208/50 3,524,806 8/1970 Case 208/46 3,673,080 6/1972 Schlinger eta1. 208/131 Primary Examiner-E. J. Meros Attorney, Agent, or Firm-T. H.Whaley; C. G. Ries 57 ABSTRACT 3 Claims, 1 Drawing Figure 1 MANUFACTUREOF PETROLEUM COKE This is a division, of application Ser. No. 831,543,filed June 9, 1969, now US. Pat. No. 3,673,080.

BACKGROUND OF THE INVENTION 1. Field of the Invention This inventionrelates to an improvement in the manufacture of petroleum coke. Morespecifically it relates to producing clusters of petroleum coke pelletsby an zmproved delayed coking process.

2. Description of the Prior Oart Regular petroleum coke as made by thewell known delayed coking process" consists of dehydrogenated andcondensed hydrocarbons of high molecular weight in the form of a uniformunsubdivided matrix of considerable physical extent containing dispersedthroughout petroleum sased aliphatic-like compounds.

In the regular delayed coking process, oil is charged into afractionating tower. The bottoms from the fractionating tower are heatedand introduced into a coke drum where coke is formed. Coke made by theregular delayed coking process is amorphous and generally soft. Further,the density of such material is low, its porosity is high, and it isweak in compression. Accordingly, such coke may be'unsatisfactory foruse in metallurgical processes, such as for example in a blast furnacewhere coke beds must support without crushing the weight of upper bedscontaining iron ore and limestone.

SUMMARY This invention pertains to a process for manufacturing clustersof petroleum coke pellets which are characterized by unusually highcompressive strength, high density, and low porosity. More particularly,the invention relates to the discovery that fused clusters of petroleumcoke pellets from about l/32 to diameter may be formed by heating in acoking heater under controlled thermal cracking conditions a highboiling liquid petroleum feedstock containing dispersed throughoutminute seed particles such as particulate carbon soot or a combinationof particulate carbon soot and catalyst fines. The partially crackedeffluent from said coking heater is introduced into a coke drum wherepetroleum coke pellets are produced and are consolidated, formingclusters of coke pellets and balls ranging in diameter from about I to 6inches.

The principal object of this invention is to produce clusters ofspheroidal shaped solid petroleum coke pellets of improved compressivestrength by cracking and polymerizing a high boiling liquid petroleumfeedstock containing seed particles, e.g., carbon soot or particulatecarbon plus catalyst fines.

This and other objects will be obvious to those skilled in the art fromthe following disclosure.

DESCRIPTION OF THE INVENTION Feedstream according to the process of thepresent invention a conventional coking heater may be charged with afeedstream of high boiling liquid petroleum feed taken from the bottomsof a vacuum tower or a fractionator; for example, the bottoms from adistillation column fed with petroleum liquids such as virgin crude,reduced crude, heavy slops and naphthas, residual fuel oil, decanted oilfrom a catalytic cracker, heavy fuel oil slurry, heavy gas oils, andmixtures fresh feed to the fractionator may contain up to about thereof.Included in said feedstream to the coking heater is about 0.01 to about0.5 wt. percent or higher of particulate carbon. Amounts above 0.5 wt.percent do not materially enhance the process. The particulate carbonmay be added to the'high boiling liquid feedstream as dry particulatecarbon soot; or it may be part of a residue slurry of particulate carbonin fuel oil which is supplied to said fractionator as part of the feed.

Such a fuel oil-particulate carbon slurry may be prepared by the carbonrecovery process described in US. Pat. No. 2,992,906 issued to Frank E.Guptill, Jr. In said process, very fine carbon particles entrained inthe gaseous products of reaction of fossil fuels and oxygen areseparated from the product gas by scrubbing the gaseous products withwater, forming a particulate carbon-water slurry. This particulatecarbon-water slurry is contacted with a light liquid hydrocarbon,forming a slurry of particulate carbon in light liquid hydrocarbon. Aheavy liquid hydrocarbon, e.g., fuel oil, is then mixed with said lightliquid hydrocarbon carbon slurry and then the light liquid hydrocarbonis distilled off leaving said slurry residue of particulate carbon sootin heavy fuel oil. Alternately, the particulate carbon-light liquidhydrocarbon slurry may be fed to the fractionator.

Electron micrographs of the carbon soot particles show that theyresemble small spheres of sponge like texture that may range in sizefrom about 0.01 to 0.5 microns but which are usually about millimicronsin diameter. Because of this structure the carbon has a tremendouslyhigh surface area, for example from about 300 to 1,000 square meters pergram. Particulate carbon soot is both oleophilic and hydrophilic. Onegram of soot will absorb about 2-3 cc of oil. A typical analysis of theparticulate carbon soot comprises in weight percent: carbon 92 to 94,hydrogen 0.4 to 1.1, sulfur 0.3 to 0.6, and ash 3.4 to 4.7.

In another embodiment of this invention the feedstream to the cokingheater may contain about 0.003 wt. percent or more of catalyst fines inaddition to the aforesaid particulate carbon. The catalyst fines may beadded to and mixed with the high boiling liquid feedstream to the cokingheater; or the catalyst fines may be part of the decanted oil which issupplied to said fractionator as part of the fresh feed. For example,

30 weight percent of fluid cracked heavy cycle gas oil from a catalyticcracker regenerator, also known as FCI-ICGO (Decanted Oil). About 0.04to 0.40 lbs. or more of catalyst fines may be present in each gallon ofFCHCGO oil charged. The bulk of the fines have a particulate size rangeof about 1 to microns. Composition of the catalyst may be approximately50 percent aluminum oxide (AI O with the bulk of the remainder beingsilicon dioxide.

The effluent from off the top of the coke drum comprising essentiallyhydrocarbon vapors and optionally a comparatively small amount of watervapor is also charged into the fractionator.

Fractionator the fractionator for producing the high boiling liquidpetroleum feed is operated at a pressure in the range of 7 to 12 psigand a temperature in the range of 275 to 750F. Pressure gas oil yieldsfrom the fractionator amount to about 60 to 65 weight percent, basisfresh feed to fractionator, and include light, intermediate, and heavygas oils varying individually with end point specifications. Otherproducts from the fractionator include: propylene and butylene feedstock(about 13.5 wt. percent), light and heavy naphthas (about 10-18 wt.percent), and fuel gas (about 1 to wt. percent).

Feedstreams to the fractionator which have a high salt content may bedesalted by conventional desalting techniques in order to prevent thefouling of heat exchange surfaces and the plugging of heater tubes. Forexample, the crude feedstock may be intimately mixed with water,caustic, and a demulsifying agent to dissolve salt and bottoms sediment.Water is then electrostatically separated from the oil, carrying alongthe inorganic impurities. The caustic ahd demulsifant aid in theseparation.

Vacuum Tower the bottoms from the fractionator containing essentiallyall of the aforesaid carbon soot and catalyst fines may be introduceddirectly into a coking heater or preferably into a conventional vacuumdistillation tower where under a vacuum of about 19-30 mm of mercuryfurther separation of the lighter components from the charge stock iseffected. With the vacuum tower on-stream, the total gas oil yield(pressure gas oil +vacuum gas oil) will be greater than the gas-oilyield without a vacuum tower in the line.

Besides maximizing the gas-oil yield, the vacuum tower alters thecomposition of the feed to the coking heater in the next step, e.g.,increases specific gravity, viscosity, ash content and concentration ofseed particles. The effect of operating with the vacuum tower in theline as compared to operating without the vacuum tower and dischargingthe bottoms from the distillation tower directly into the coking heateris shown in Table I. Most of the properties of the charge stock to thecoking heater increase when the vacuum tower is in the line. Further,the effect on the product is beneficial as the coke pellets appear finerand unite better in a cluster.

TABLE I Coking Heater the coking heater serves as a thermal crackingreactor. The charge to the coking heater may be the seeded hot heavyresiduum from the bottom of the vacuum tower or from the bottom of thefractionator. The coking heater charge in weight percent (basis freshfeed charged to the fractionator) is in the range of about 53 to 66 withthe vacuum tower on and about 74 to 94 with the vacuum tower down. Highboiling residuums having the desired composition may be also introducedinto the process at this point.

The coking heater may comprise an externally fired heating coil of suchdesign as to effect a rapid heating of the oil to a predeterminedtemperature and a minimum soaking time, thereby controlling the crackingof the oil while it is in the coil. In the cracking reaction, largemolecules are split into two or more smaller molecules. Thermal crackingstarts at a temperature of about 750F. and the rate of reaction doublesfor every 25F. increase in reaction temperature. Polymerization andcondensation reaction wherein two molecules combine to form a largermolecule are prevented from proceeding in the coil to the point wherecoke is formed. Rather, such solid forming reactions are delayed untilthe effluent from the coking heater is charged into the coke drum.

The coking heater may be one of conventional design wherein the feed isheated from an inlet temperature in the range of about 650 to 720F. to asufficiently high temperature so that thermal cracking occurs at a rapidrate. However, residence time is controlled and kept to a minimum sothat only about 30 percent of the thermal cracking is completed in thecoil.

The coking heater outlet temperature is controlled at a temperature inthe range of 900 to 930F. Higher temperatures may cause rapid coking inthe coking heater and shorten on stream time. Lower temperatures producesoft coke with a high VCM (volatile High Boiling Pet- High BoilingPetroleum Oil Madc Without Vacuum Tower in line rolcum oil Made withVacuum Tower Operating (Vacuum Tower Hot- Property (FractionatorBottoms) toms) Gravity, AP1 8.0 12.0 3.0 7.0 Sp. Gr. at 60F. 0.986 1.0141.022 1.052 Sulfur, wt. 1.2 1.5 1.5 2.0 Basic N ppm 3,000 4,000 5,0006,000 Viscosity, SFS at 210 F. 200 600 500 1,000 Salt Content.Grams/bbl. 15 20 20 Ash, wt. 0.03 0.07 0.05 0.10 Conradson Carbon, wt.7: 11.0 14.0 17.0 22.0 Metals, ppm.

Ni 60 V 60 75 75 100 FE 7O Free Carbon Soot Content wt. 7 0.04 0.10 0.120.28 Cataly st Content.

lhlgal. 0.003 0.04 0.006 0.06 Watson Charactcrimtion Factor K, 10.6 10.810.4 10.7 Hydrogen to Carbon Weight Ratio. Min. 0.11 0.119 0.10 0.108Boiling Point at 10 mm. 10% Outrhead, F. 555 850 Optionally present\equal parts by weight of A1 0 and $10,)

combustible matter) content.

The residence time in the tubular heater must be long enough to bringthe oil up to the desired temperature. However, excess time in thetubular heater may cause coking and result in clogging the heater coil.Thus, the residence timeifi thetubiilar coil i s maintainedat about 1 to3 minutes (preferably less than 2 minutes) while at the previouslymentioned conditions of temperature and pressure.

One method for controlling the velocity, and residence time ifi theheatiiigcoil is byfiije cfingaFelatively small amount of liquid waterinto the high boiling petroleum oil feed entering the heating coil.Water injection is controlled at a rate sufficient to maintain the oilvelocity in the heating coil high enough to prevent coke from formingand depositing in the heater coil. For example, the amount of liquidwater injected into the high boiling liquid petroleum feed may vary fromabout 0.3 to 4.0 weight percent (basis oil charged to the cokingheater).

Coke Drums the hot effluent from the coking heater may comprise highboiling liquid petroleum and cracked compounds of said high boilingliquid petroleum, hydrocarbon vapors, and a comparatively small amountof water vapor. The effluent is introduced into a coke drum at atemperature in the range of 880 to 895F. and a pressure in the range ofabout 40 to 60 psig. The coke drum is stationary and consists of avertical elongated cylinder having a truncated coneshaped section at thelower end. The charge is fed to the coke drum axially at the bottom andpasses through a deflector assembly mounted on the bottom head insidethe coke drum. The deflector assembly consists of a short cylinder witha closed top and with eight elongatedvertical slots equally spacedaround the walls. These slots divide the charge into eight separatestreams. Each stream emerges radially from a slot and then swirlsupwardly as directed by the conical shaped sides which form the endsection of the vessel.

As the charge fills the coke drum, petroleum coke pellets form andcombine in clusters, in a manner to be further described. Hydrocarbonvapors at a temperature in the range of 810 to 820F. and a pressure inthe range of about to 45 psig leave from the top of the coke drum andflow into the fractionator, along with a comparatively small amount ofwater vapor, if any.

While the exact mechanism by which the petroleum coke pellets are formedand clustered is unknown, it may be postulated that in the coke drum theparticulate carbon soot dispersed in the substantially liquid charge mayserve as seeds or nucleating agents on which the hydrocarbons condense,polymerize, and crosslink. Under time-temperature conditions in thecoking zone the resulting deposit on the surface of a seed particle oron a growing coke particle undergoes dehydrogenation and the formationof a layer of coke. Repetition of this coking cycle causes successivelayers of coke to build-up on the growing particle.

Initially, the particulate carbon soot seed and the growing particleswill be in suspension in the upwardly swirling feedstream within thecoke drum. However, at some point, pellet sized particles will settleout by gravity and deposit on and fuse with other coke pellets at thebottom of the coke drum, forming a cluster of petroleum coke pellets.The pellets harden and the level of the coke bed raises until a batch ofclustered petroleum coke pellets fills the coke drum.

In appearance, the petroleum coke pellet clusters may take on severalforms. For example, in a preferred embodiment of the invention with thevacuum tower in the line, the subdivided spheroidal shaped petroleumcoke pellets about 1/32 to A inches in diameter are fused to contiguouspellets to form a cluster. In another form, the petroleum coke pelletsare partially fused to contiguous pellets and partially bonded to eachother by means of from about 2 to 30 weight percent of a solidasphaltic-like material as produced along with the pellets during thecoking of said high boiling petroleum .oil. A variation of this lastform consists of spheroidal shaped clusters of said fused and bondedpetroleum coke pellets wherein the diameter of the spheroid is about 1to 6 inches and the outer surface is smooth.

When a coke drum has been filled with a batch of hardened coke clustersto a desired level, it is taken out of service and decoked. First,superheated steam is put into the coke drum at the bottom, to displacehydrocarbon vapors and to remove high boiling point hydrocarbonsremaining on the coke. Then, after the coke drum has been steamed for asufficient length of time, e.g., about 1 to 3 hrs. to producespecification VCM coke, the coke drum is filled with water and cooled.The water is then drained from the cooled coke drum, and the top andbottom heads are removed. An axially aligned hole is cut verticallythrough the coke bed to permit the introduction of high pressure jetstreams of water. By this means, the batch of petroleum coke is brokenup into lumps and removed from the bottom of the drum.

The coke yield, basis weight percent of coking heater charge is in therange of 20 to 26 with the vacuum tower on and from about 17 to 21 withthe vacuum tower down.

The petroleum coke produced by the process of our discovery ischaracterized by the properties shown in Table II. When tested by meansof a Chatillion light spring tester, a Vs inch diameter pellet willwithstand a compressive load of 17 pounds average and about 14 poundsminimum. In comparison, a comparable sized piece of regular petroleumcoke will fail at a compressive load of 8 pounds average and about 6pounds minimum. Further, the petroleum coke does not degrade duringhandling; that is, there is no increase in fines not other sizingchanges during movement and stockpiling.

Undesirable adulterating products may be removed from the petroleum cokeby calcining the coke in a rotary kiln at a temperature in the range ofabout l,000 to 1,500C.

TABLE II PROPERTIES OF SPHEROIDAI. PETROLEUM COKE CLUSTERS DESCRIPTIONOF THE DRAWING A more complete understanding of the invention may" behad by reference to the accompanying schematic drawing which shows thepreviously described process in detail. Although the drawing illustratesa preferred embodiment of the process of this invention, it is notintended to limit the invention to the particular apparatus or materialsdescribed.

With reference to the drawing, fresh feed consisting of heavy slops andnaphtha in line 1, a mixture of crude oils, fuel oil, and if presentdecanter oil from a catalytic cracker containing catalyst fines in line2, and slurry oil containing particulate carbon from a synthesis gascarbon recovery system in line 3 are introduced into fractionator 4.Coke drum vapor and optionally a comparatively small amount of steamfrom coke drums 5 and 6 are also introduced into fractionator 4 by wayof line 7.

Over a temperature range of about 275 to 750F. and a pressure range ofabout to 25 psig the aforesaid feed is separated into various productstreams. For example, the following streams are taken from thefractionating tower: light, intermediate and heavy gas oils throughlines 8, 9 and 10 respectively. Overhead products such as the followingare removed through overhead line 11: propylene and butylene feedstock,light and heavy naphtha, water, and fuel gas.

In a preferred embodiment, with valve 12 closed and valve 13 open thebottoms from fractionator 4 at a temperature in the range of about 710to 725F. and a pressure of about 12 psig are passed through line 14, 15and 16 into vacuum tower 17. Vacuum gas oil is removed from the vacuumtower through lines 18 to 21.

Vacuum residuum, at a pressure of about 30 mm of mercury and atemperature in the range of about 600 to 690 F. is removed from thebottom of vacuum tower 17 through lines 22 to 24 and valve 25.

By means of pump 26, line pressure is increased to about 300 to 600 psigand the vacuum residuum is passed through lines 27 and 28 and intocoking heater 29. Liquid water may be injected into the high boilingpetroleum oil in line 27 by way of lines 30 and 31. Metering valve 32controls the rate of water injection.

From line 33 at the exit of coking heater 29, the hot effluent at anexit temperature in the range of about 900 to 930F. and a pressure inthe range of about to 60 psig is passed into coke drum 5 by way of lines34 to 36, and control valve 37. While coke drum 5 is being filled, valve38 is closed and coke drum 6 is being decoked. After coke drum 5 hasbeen filled, valve 37 is closed, valve 38 is opened, and coke drum 6 isfilled by way of lines 33, 39, 40 and 41 while drum 5 is being decoked.

The effluent from coking heater 29 enters at the bottom of coke drum 5,emerging through eight vertical slots, for example 42 and 43, in theside wall of deflector assembly 44. Similarly, during the filling ofcoke drum 6, the effluent from coking heater 29 emerges through eightvertical slots, for example, 45 and 46, in the side walls of deflectorassembly 47.

During the filling of coke drum 5, overhead valves 48 and 49 are closedand valve 50 is opened. Hydrocarbon effluent vapors and perhaps acomparatively minor quantity of steam are removed from the top of cokedrum 5 and are introduced into fractionator 4 as previously described,by way of lines 51 to 53 and line 7.

Similarly, while coke drum 6 is being filled valves 50 and 54 areclosed, valve 49 is opened, and overhead effluent vapors from coke drum6 are sent to the fractionator by way of lines 55 to 57, and line 7.

Steaming of the coke to control its VCM is'accomplished at a temperatureof about 910F. Steam in line 58 may be introduced into the bottom ofcoke drum 5 through lines 59 and 36 by opening valve 60 and closingvalve 37. Overhead valve 50 is closed and valve 48 is opened to permitthe steam and hydrocarbon vapors from coke drum 5 to pass through lines51, 61 and 62 and into a unit, not shown, for separating sour water fromintermediate gas oil. In a similar manner, by closing valves 38 and 49,and opening valves 63 and 54, steam in line 64 may be passed throughlines 65, 41, coke drum 6, and lines 55, 66, 67, and into an oil-waterseparating unit.

Cooling water enters at the top of the coke drum through lines'not shownand discharges from the bottom. After the top and bottom covers areremoved from a coke drum, the petroleum coke inside is broken up by highimpact water jet and is removed through lines 68 and 69 at the bottom ofcoke drums 5 and 6 respectively. Lumps of petroleum coke clusters aresent to storage through line 70.

Altemately, when it is desirable to use the bottoms from thefractionating tower as the high boiling petroleum feed to the cokingheater, vacuum tower 17 may be removed from the line by closing valves13 and 25 and opening valve 12. Fractionator bottoms are then introduceddirectly into coking heater 29 by way of lines 14, 71, 72, 24, 27, and28.

EXAMPLE OF THE PREFERRED EMBODIMENT The following is offered in a betterunderstanding of the present invention, but the invention is not to beconstrued as limited thereto.

TABLE 1V COMPOSITION OF CHARGE STOCK TO FRACTIONATOR Fluid CrackedCalifornia Fuel Oil- Heavy Cycle San Ardo California Reduced Heavy SlopsCarbon Gas Oil with Crude Crude Crude and Naphthas Slurry CatalystDensity 0976-0983 0.904-0.947 0973-0993 0904-0986 0994-1034 0973-1037Viscosity SSU at 100F. 15000-221100 5003,000 100-].500 200-400 SSU at210F. LOCO-2,000 SFS at 122F. 300-700 -5.5-15- 0I,000 Gravity. API 12-1418-25 11-14 12-25 5.5-11 5-14 Ash. wt. X 0.04-0.06 0.5-1.5 0.0-1.00.05-0.15 Metals. ppm

Ni 150-80 20-80 60-100 0.100 10-50 V -110 30-150 50-80 0.100 -200 TABLEIV-Cpntinued COMPOSlTlON OF CHARGE STOCK TO FRACTIONATOR Fluid CrackedCalifornia Fuel Oil- Heavy Cycle San Ardo California Reduced Heavy SlopsCarbon Gas Oil with Crude Crude Crude and Naphthas Slurry CatalystSulfur. wt. a |-2 l-2 l-2 0.8-2.0 1.2-1.5 ""di's iIi' Conradson Carbon,Wt. 7r 10- 12 10-14 2-10 12-17 1.2-3.5 Carbon Soot. wt. 7r 0 0 0 03.0-7.0 0 Catalyst Content, I lbs/gal 0 0 0 0 0 0.04-0.40Characterization Factor, K 11.3-11.7 11.5-11.9 11.6-11.8 10.5-12.010.7-11.2 10.5-11.2 Salt Content,

Grams/bbl. -40 -50 5-50 0-25 -25 0 Usual Volume Range. 12-72 0-23 17-602.5-26.0 0.5-2.0 0-30 Equal parts by weight of Al oyand SiO;

With referenceto drdpr ocess shown iiuthe drawingi a fresh feedstream ofabout 60,300 BPSD* of mixed petroleum feedstocks as shown in Table 111and having the properties as shown inTable 1V is introduced into afractionator. In addition, about 26,180 BPSD of hydrocarbon effluentvapor (basis feed to coke drum) and about 274 BPSD of Steam are fed intothe fractionator.

TABLE I11 FRESH FEED TO FRACTlONATOR About 47,000 BPSD of highboilingpetroleum oil of' about 12AP1 from the bottom of the fractionator at atemperature of about 730F. and a pressure of about 12 psig areintroduced into a vacuum tower. Other streams removed from thefractionator include: about 10,000 BPSD of intermediate gas oil of about28AP1 at a temperature of about 520F; about 12,000 BPSD of heavy gas oilof about 23AP1 and a temperature *BPSD means barrels (42 gallons perbarrel) per standard operating day (24 hours.) of about 690F; about11,000 BPSD of light gas oil of about 34AP1 and a temperature of about-415F; and about 7,214 BPSD of miscellaneous and overheadproducts'including propylene and butylene feedstocks, light and heavynaphtha, H 0, and fuel gas.

About 12,000 BPSD of vacuum gas oil are removed from the vacuum tower ata temperature of about 550F. and a pressure of about 22 mm of mercury.Another stream of about 500 BPSD of vacuum gas oil is removed fEHthetowerafa temperature of 555m 175F. and a pressure of about 17 mm ofmercury. These two streams are combined yielding 12,5 OO'BPSD of vacuumgas oil of about 17AP1.

34,000 BPSD of vacuum tower bottoms of about 3 sure of about 30 mm ofmercury are removed from the bottom of the vacuum tower and pumped [t apressure of about 55 psig to the coking heater. Along the way about 274BPSD of liquid water are injected into the high boiling petroleum oil.The coking heater is a four coil externally fired tubular heater. Eachoil has an inside diameter of three and seven-eighths inches and isabout 3,000 feet long. The vacuum tower bottoms feed stream is dividedinto four equal streams, one to each coil. A pressure differential ofabout 250 psig across the coil is required to send the high boilingpetroleum oil through the heating coil at a velocity of about 10 feetper second at the inlet and about feet per second at the outlet.

The effluent from the heater at a temperature of about 907F. isintroduced into one of a pair of coke drums at a temperature of about885F. and a pressure of about 45 psig. While one coke drum is beingfilled, the other is being decoked. The tum-around time for each cokedrum is about 28 hours. During the coking reaction about 26,180 BPSD ofeffluent vapors (basis feed to coking heater) and a relatively smallamount of water vapor (about 274 BPSD) are removed from the top of thecoke drum and passed to the fractionator as previously described.

After a coke drum is filled with coke to a desired level, it is takenout of service and decoked. About 15,000 lbs. per hour of superheatedsteam is flowed then upwardly through the coke drum to displace residualhydrocarbon vapors and to remove any high boiling point hydrocarbonsremaining on the coke. The coke is steamed for about three hours oruntil the Volatile Combustible Matter (VCM) in weight percent is in therange of 8.0 to 29.5 and preferably in the range of 9.5 to 11.0.

About 100,000 lbs/hr. of water are then flowed through the coke drum forabout 3 hours to cool the coke to a temperature of about 200F. or less.After the water is drained out, the coke drum is opened, a hole is cutdown the vertical axis of the coke bed, and the coke is removed with theaid of high pressure water jets.

About 7,820 BPSD of the high boiling petroleum feed to the coking heateris converted to about 1,380

tons per day of petroleum coke pellet clusters. The petroleum coke isremoved from the coke drum and is sluiced with water into a coke pit.Chunks of petroleum coke clusters are then separated from the water,removed from the coke pit, and transported by conveyor to the cokestorage area.

The coke pellet clusters may be broken into small lumps and used as isfor metallurgical purposes. Or, by calcining at a temperature of aboutl,000 to l,500C., the density of the coke may be increased and certainimpurities removed.

A visual examination of the product petroleum coke shows it to becomposed of subdivided solid carbon spheroidal pellets about l/32 to Ainch diameter loosely fused together in a cluster. A fraction of theclusters are ball-shaped with smooth polished surfaces. Such balls mayrange in diameter from about 1 inch to inches and are randomly dispersedthroughout the coke drum.

The process of the invention has been described generally and byexamples with reference to various com positions of high boilingpetroleum oils, seed particles and nucleating agents, and various othermaterials of particular composition for purposes of clarity andillustration only. From the foregoing it would be apparent to thoseskilled in the art that the various modifications of the process, thematerials, and the amounts of the materials disclosed herein can be madewithout departure from the spirit of the invention.

We claim:

1. A petroleum coke composition consisting of a cluster of solidpetroleum coke spheroidal pellets, each pellet having a nucleus and anoutside diameter in the range of about 1/32 to A inch and being at leastpartially fused and bonded to continguous pellets in said cluster withabout 2 to 30 weight percent of a solid asphaltic-like material. andsaid petroleum coke pellets and solid asphaltic-like material beingsimultaneously produced by the delayed coking of a dispersion comprisinghigh boiling liquid petroleum oil containing dispersed throughout about0.01 to about 0.5 wt. percent minute particulate carbon soot seedparticles produced by the partial oxidation of fossil fuels whichconstitute the said nucleus of said petroleum coke pellets and whichhave'a diameter in the range of about 0.01 to 0.5 microns, an oilabsorption No. of about 2-3 cc of oil per gram of carbon soot, and asurface area of about 300l,000 square meters per gram; and wherein saidpetroleum coke pellets will withstand a compressive load of 14 poundsminimum when a /8 inch diameter pellet is tested by means ofa Chatillionlight spring tester and are formed and fused together by mixing 0.3 to4.0 weight percent of liquid water with said dispersion and heating themixture in a heating zone over a temperature range of about 650 to 930F.for about 1 to 3 minutes to control cracking, followed by delayed cokingat a temperature in the range of about 800 to 895F. and a pressure inthe range of about 20 to 60 psig.

2. The petroleum coke composition of claim 1 externally shaped in theform of a spheroid having a diameter in the range of about 1 to 6 inchesand with a smooth outer surface.

3. The petroleum coke composition of claim 1 wherein said high boilingliquid petroleum oil also contains at least about 0.003 pounds ofcatalyst fines comprising aluminum oxide and silicon dioxide per gallonof said liquid petroleum feed.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION PATENT NO. 385g,olr7 May 2'7, 1975 DATED December 3, 97

|NVENT0R(5 i W. SCHLINGER H. KAUFMAN C. CROWLEY It is certified thaterror appears in the above-Identified patent and that said LettersPatent are hereby corrected as shown below:

Col. 1., line 12 Change "Oart" to --ART-- Col. 1, line 18 Change "sased"to --based-- TABLE IV Under column headed "Heavy Slops and NaphtnaDelete 5.5 l5 Delete "O-l,OOO

TABLE IV Under col. headed "Fuel Oil Carbon Slurry" Insert --l50-lOOO--opposite SFS at 122F.

Col. 9, lines 55-56 Relocate the following "*BPSD means barrels (#2gallons per barrel) per standard operating day (2 L hours.)"

"[1! to a Col. 10, lines 23 and 25 Change Col. 10, line 29 Change "oil"to --coil-- Signed and Scaled this RUTH C. MASON Arresring Officer C.MARSHALL DANN (ummixsiunvr vfParenrs and Trademarks

1. A PETROLEUM COKE COMPOSITION CONSISTING OF A CLUSTER OF SOLIDPETROLEUM COKE SPHEROIDAL PELLETS, EACH PELLET HAVING A NUCLEUS AND ANOUTSIDE DIAMETER IN THE RANGE OF ABOUT 1/32 TO 1/4 INCH AND BEING ATLEAST PARTIALLY FUSED AND BONDED TO CONTINGUOUS PELLETS IN SAID CLUSTERWITH ABOUT 2 TO 30 WEIGHT PERCENT OF A SOLID ASPHALTIC-LIKE MATERIAL,AND SAID PETROLEUM COKE PELLETS AND SOLID ASPHALTIC-LIKE MATERIAL BEINGSIMULTANEOUSLY PRODUCED BY THE DELAYED COKING OF A DISPERSION COMPRISINGHIGH BOILING LIQUID PETROLEUM OIL CONTAINING DISPERSED THROUGHOUT ABOUT0.01 TO ABOUT 0.5 WT. PERCENT MINUTE PARTICULATE CARBON SOOT SEEDPARTICLES PRODUCED BY THE PARTIAL OXIDATION OF FOSSIL FUELS WHICHCONSTITUTE THE SAID NUCLEUS OF SAID PETROLEUM COKE PELLELTS AND WHICHHAVE A DIAMETER IN THE RANGE OF ABOUT 0.01 TO 0.5 MICRONS, AN OILABSORPTION NO. OF ABOUT 1-3 CC OF OIL PER GRAM OF CARBON SOOT, AND ASURFACE AREA OF ABOUT 300-1,000 SQUARE METERS PER GRAM; AND WHEREIN SAIDPETROLEUM COKE PELLETS WILL WITHSTAND A COMPRESSIVE LOAD OF 14 POUNDSMINIMUM WHEN A 1/8 INCH DIAMETER PELLET IS TESTED BY MEANS OF ACHATILLION LIGHT SPRING TESTER AND ARE FORMED AND FUSED TOGETHER BYMIXING 0.1 TO 4.0 WEIGHT PERCENT OF LIQUID WATER WITH SAID DISPERSIONAND HEATING THE MIXTURE IN A HEATING ZONE OVER A TEMPERATURE RANGE OFABOUT 650* TO 930**F. FOR ABOUT 1 TO 3 MINUTES TO CONTROL CRACKING,FOLLOWED BY DELAYED COKING AT A TEMPERATURE IN THE RANGE OF ABOUT 800*TO 895*F. AND A PRESSURE IN THE RANGE OF ABOUT 10 TO 60 PSIG.
 2. Thepetroleum coke composition of claim 1 externally shaped in the form of aspheroid having a diameter in the range of about 1 to 6 inches and witha smooth outer surface.
 3. The petroleum coke composition of claim 1wherein said high boiling liquid petroleum oil also contains at leastabout 0.003 pounds of catalyst fines comprising aluminum oxide andsilicon dioxide per gallon of said liquid petroleum feed.